Threats / Google / CVE-2021-30633
CVE-2021-30633
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-06-22
Google Chromium Indexed DB API vulnerability
Use-after-free in Chromium Indexed DB API allows sandbox escape when renderer process is compromised via crafted HTML.
Verdict
Today item — known-exploited.
A use-after-free vulnerability in the Indexed DB API enables attackers with renderer process control to escape the sandbox. Exploitation requires prior compromise and crafted HTML delivery, but impacts confidentiality and integrity across Chromium-based browsers.
01
Is it exploitable?
— the evidence, ranked above the scoreReported exploitation
2 independent public reports of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2021-11-03).
Probability (EPSS)
EPSS 0.32657 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
Affected: Google, Chromium Indexed DB API. Confirm exact fixed builds in the vendor advisory.
Weakness (CWE)
Mapped to CWE-416 Use After Free — weakness family: Memory safety.CWE assignment from the public NVD record; the weakness class drives how the flaw is exploited.
02
Who’s exploiting it?
— attribution turns risk into urgencyAttribution not established
No confirmed (advisory-backed) threat-actor attribution is established for this record. Absence of a named actor is not absence of compromise — see Coverage & confidence.
03
Why it matters
— the attack path, told twice: adversary, then board1
Front door — unauthenticated access narrative 1
Attacker
I deliver a crafted HTML page to a target user in a Chromium-based browser.
Business
User visits attacker-controlled or compromised web content, initiating the attack chain.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I trigger the use-after-free in the Indexed DB API to compromise the renderer process.
Business
Renderer process isolation is breached, allowing code execution beyond normal web sandbox constraints.
3
Lateral reach — past segmentation narrative 3
Attacker
I leverage the compromised renderer to escape the browser sandbox and access system resources.
Business
Attacker gains elevated privileges and can access sensitive user data, install malware, or pivot to system compromise.
04
What to do
— defensible action- Remediate per the vendor advisory — confirm the fixed build for your version and verify exposure.1
Say it to the boardA vulnerability with this evidence profile is a defensible budget line, not a backlog ticket — fund the change against the proof above.
05